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LA student following the procedure described in this experiment collected the fo

ID: 917282 • Letter: L

Question

LA student following the procedure described in this experiment collected the following data, mass Mg. g 0.0243 volume of gas, mL 25.5 barometric pressure, mm Hg 755 temperature. K 298 Calculate the value of the gas law constant, R. How many grams of Mg must react with HCI(aq) in order to produce 80.0 ml. of hydrogen gas at STP? Use the value for R that you calculated in question 1. If the temperature and pressure remain constant, how does the volume of a gas sample vary with the number of moles of gas present?

Explanation / Answer

1 ) PV=nRT

   ( 755/760)(25.5/1000) = (0.0243/24.3)R (298)

R = 0.085

2)      Mg   + 2HCl   ------->   MgCl2 + H2

No of moles of H2 = 80/22400 = 3.57 millimole = Moles of Mg needed as per stiochiometry

Mass of Mg = 3.57 x 24.3 = 0.08678 gram

3) for constant T and Pressure,

V is directly propotional to no of moles

V   n